A barge can be a very efficient mode of transportation for transporting large volumes of loose material such as gravel, grain and the like. The barge size is limited by the restrictions in the waterway, e.g., the water depth, the locks through which the barge must pass, etc. These restrictions for many navigable waterways nevertheless permit the use of a very large barge to the extent that the greater problem is efficient loading and unloading of the material to and from the barge.
Loading and unloading operations also require special consideration to insure that the load on the barge at any point in time is not unduly unbalanced. During loading and unloading, should it happen that one end versus the other, or one side versus the other, is substantially unbalanced, the barge could overturn. Even loading both ends and not the middle can severely strain the structure as the ends are held down by the load and the buoyancy of the unloaded middle results in an upward thrust that produces a bending force. Even providing the completed load with a crown, i.e., more load in the center of the barge, is not desirable if such raises the center of gravity and renders the barge more likely to tip, e.g., in severe weather conditions.
There are two common methods of unloading a barge. The first is the use of a crane fitted with a clam shell bucket and the barge is unloaded bucket load by bucket load. To apply such a method to a barge of the size contemplated herein would require that the barge be tied up for days and such is not acceptable. A much faster unloading method is the self-unloading barge wherein the barge is designed to have a conveyor under the hold of the barge, the hold is provided with a bottom channel that overlies the conveyor. For unloading the channel is opened and allows the material to gravity feed onto the conveyor and the conveyor conveys the material through conveyor linkages onto the shore. This latter design requires concessions in the design of the hold, e.g., converging sides that narrow to the channel for gravity feed, and such concessions substantially impact on the capacity of the hold. Both methods require precautions to avoid load imbalance.
It is accordingly an object of the present invention to provide efficient and even loading and unloading of a barge, which is primarily applicable to a flat bottomed, straight side walled hold for a barge that is very large in its capacity.